HCoop / hcoop / debian / mlton.git / blame
| Commit | Line | Data |
|---|---|---|
| 7f918cf1 CE |
1 | DeadCode |
| 2 | ======== | |
| 3 | ||
| 4 | <:DeadCode:> is an optimization pass for the <:CoreML:> | |
| 5 | <:IntermediateLanguage:>, invoked from <:CoreMLSimplify:>. | |
| 6 | ||
| 7 | == Description == | |
| 8 | ||
| 9 | This pass eliminates declarations from the | |
| 10 | <:BasisLibrary:Basis Library> not needed by the user program. | |
| 11 | ||
| 12 | == Implementation == | |
| 13 | ||
| 14 | * <!ViewGitFile(mlton,master,mlton/core-ml/dead-code.sig)> | |
| 15 | * <!ViewGitFile(mlton,master,mlton/core-ml/dead-code.fun)> | |
| 16 | ||
| 17 | == Details and Notes == | |
| 18 | ||
| 19 | In order to compile small programs rapidly, a pass of dead code | |
| 20 | elimination is run in order to eliminate as much of the Basis Library | |
| 21 | as possible. The dead code elimination algorithm used is not safe in | |
| 22 | general, and only works because the Basis Library implementation has | |
| 23 | special properties: | |
| 24 | ||
| 25 | * it terminates | |
| 26 | * it performs no I/O | |
| 27 | ||
| 28 | The dead code elimination includes the minimal set of | |
| 29 | declarations from the Basis Library so that there are no free | |
| 30 | variables in the user program (or remaining Basis Library | |
| 31 | implementation). It has a special hack to include all | |
| 32 | bindings of the form: | |
| 33 | [source,sml] | |
| 34 | ---- | |
| 35 | val _ = ... | |
| 36 | ---- | |
| 37 | ||
| 38 | There is an <:MLBasisAnnotations:ML Basis annotation>, | |
| 39 | `deadCode true`, that governs which code is subject to this unsafe | |
| 40 | dead-code elimination. |